DOCSLIB.ORG

Module 13: Critical Flow Phenomenon Joseph S. Miller, PE

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Module 13: Critical Flow Phenomenon Joseph S. Miller, PE Fundamentals of Nuclear Engineering Module 13: Critical Flow Phenomenon Joseph S. Miller, P.E. 1 2 Objectives: Previous Lectures described single and two-phase fluid flow in various systems. This lecture: 1. Describe Critical Flow – What is it 2. Describe Single Phase Critical Flow 3. Describe Two-Phase Critical Flow 4. Describe Situations Where Critical Flow is Important 5. Describe origins and use of Some Critical Flow Correlations 6. Describe Some Testing that has been Performed for break flow and system performance 3 Critical Flow Phenomenon 4 1. What is Critical Flow? • Envision 2 volumes at different pressures suddenly connected • Critical flow (“choked flow”) involves situation where fluid moves from higher pressure volume at speed limited only by speed of sound for fluid – such as LOCA • Various models exist to describe this limiting flow rate: • One-phase vapor, one phase liquid, subcooled flashing liquid, saturated flashing liquid, and two-phase conditions 5 2. Critical Single Phase Flow Three Examples will be given 1.Steam Flow 2.Ideal Gas 3.Incompressible Liquid 6 Critical Single Phase Flow - Steam • In single phase flow: sonic velocity a and critical mass flow are directly related: g v(P,T)2 a2 = c dv(P,T) dP S 2 g G = a2 ρ(P,T )2 = c crit dv(P,T ) dP S • Derivative term is total derivative of specific volume evaluated at constant entropy • Tabulated values of critical steam flow can be found in steam tables 7 Example Critical Steam Flow Calculation • Assume 2 in2 steam relief valve opens at 1000 psi • What is steam mass discharge rate? • Assume saturated system with Tsat = 544.61°F • f = 50.3 • Wcrit = f P A =(50.3lb-m/hr)(1000 psi)(2 in2) = 100,600 lb-m/hr = 27.94 lb-m/sec. 8 Mass flow rate of a gas at choked conditions for Ideal Gas All gases flow from upstream higher stagnation pressure sources to downstream lower pressure sources. There are several situations in which choked flow occurs, such as: change of cross section (as in a convergent- divergent nozzle or flow through an orifice plate. When the gas velocity is choked, the equation for the mass flow rate in SI metric units is: m = or for an ideal gas m = where: m= mass flow rate, kg/s C = discharge coefficient, dimensionless (usually about 0.72) A = discharge hole cross-sectional area, m² k= cp/cv of the gas cp = specific heat of the gas at constant pressure cv = specific heat of the gas at constant volume ρ = real gas density at P and T, kg/m³ P= absolute upstream stagnation pressure, Pa M= the gas molecular mass, kg/kmole (also known as the molecular weight) R= Universal gas law constant = 8314.5 (N·m) / (kmole·K) T= absolute gas temperature, K Z= the gas compressibility factor at P and T, dimensionless 9 Critical Single Phase Flow – Incompressible Liquid (Lahey and Moody, Ref. 1) Where throat pressure, pr, is equal to the downstream receiver pressure, pR, and Gl, is the so-called Bernoulli mass flux. 10 Critical Single Phase Flow – Ideal Gas(Lahey and Moody, Ref. 1) (cont) 11 Ideal Gas Flow Rate 12 3. Two-phase Critical Flow Using Moody Equilibrium Flow Model (Refs. 1 & 2) 13 Two-phase Critical Flow Using Moody Equilibrium Flow Model (Refs. 1 & 2) 14 Two-phase Critical Flow Using Moody Equilibrium Flow Model (Refs. 1 & 2) (cont) That is, for a known stagnation state, local static pressure, p, and slip ratio, S, the flow rate unit area is uniquely determined. From numerous experimental and theoretical studies, the slip 1/2 ratio, S, has been determined to range from S = 1.0 (homogeneous) to S = (ρf / ρg) . For condition imposed by Moody, the slip ratio is evaluated as 1/3 S = S(p) = (ρf / ρg) . (9.53) Equation (9.53) shows that at a maximum G, the slip ration is a function of pressure only. Employing Eq. (9.53) in Eq. (9.52) and using saturated steam-water properties, Fig. 9-10a can be obtained, which gives Gc in terms of p0 and h0 . 15 Two-phase Critical Flow Using Moody Equilibrium Flow Model (Refs. 1 & 2) (cont) 16 Example Calculation From page 8 for sat steam at 1000 psia: Wcrit = f P A =(50.3lb-m/hr)(1000 psi)(2 in2) = 100,600 lb-m/hr = 27.94 lb-m/sec. What is this value when using Moody table on page 16? 2 Gc(P = 1000, h = 1193) = 2000 lbm/sec-ft 2 2 2 Wcrit/A = (27.94 lbm/sec)/ (2 in / 144 in /ft ) 2 Wcrit/A = 2012 lbm/sec-ft Checks 17 Two-phase Critical Flow Using Moody Homogeneous Equilibrium Model (Ref. 1 & 2) (cont) 18 Two-phase Critical Flow Comparing Moody, HEM and Bernoulli (Refs. 1 & 2) (cont) 19 Henry-Fauske/ Homogeneous Equilibrium Critical Flow Transition Model 20 Brunell Critical Flow for Flashing Water • As with anything dealing with two phase flow: • Assumed Slip Ratio affects two-phase critical flow correlations. • For example: Burnell developed critical flow correlation for flow of flashing water in short pipes and orifices 1/2 Gcrit = (2gcρl(P – (1-C)Psat)) • Other critical flow correlations exist for different assumed regimes 21 4. Where is Critical Flow Important • Used in LOCA break flow calculations • Main Steam Line Breaks • Maximum flow in a orifice • Safety Valve Opening LOCA break flow calculations • Small Breaks • Large Breaks • Intermediate Breaks • Include Break side and discharge side, especially to determine flow into a containment or sub compartment Break Flow from Discharge Pipe for double-ended Rupture Reference: NEDO 24548 ASSUMPTIONS: •The initial Velocity of the fluid in the pipe is zero. When considering both sides of the break, the effects of initial velocities would tend to cancel out. •Constant reservoir pressure at 1000 psia at saturated liquid conditions. •Initially fluid conditions inside the pipe on both sides of the break are similar. • Wall thickness of the pipe is small compared to the diameter. •Subcompartment pressure ≈ 0 psig. • Quasi-steady mass flux is calculated using the Moody steady slip flow model with subcooling. Nomenclature and Definitions ABR - Break Area, ft AL - Minimum cross-sectional area between the vessel and the break. This is the sum of the area of parallel flow paths. c1 - Sonic speed in the fluid D - Pipe inside diameter at the break location, ft FI - Inventory flow multiplier FI = 0.75 for saturated steam FI = 0.50 for liquid 2 gc - Proportionality constant (= 32.17 lbm-ft/lbf-sec ) 2 G1 - Mass Flux, lbm/ft -sec 2 Gc - Maximum mass flux, lbm/ft -sec ho - Reservoir or vessel enthalpy, BTU/lbm hp - Initial enthalpy of the fluid in the pipe, BTU/lbm LI - Inventory length. The distance between the break and the nearest area decrease of AL . - Mass Flowrate, lbm/sec - Mass flowrate during the inventory period, lbm/sec Po - Reservoir or vessel pressure, 1000 psia Psat - Saturation pressure for liquid with an enthalpy of hp t - Time, sec tI - Length of the inventory period, sec v - specific volume of the fluid initially in the pipe, ft 3/ lbm 3 VI - Volume of the pipe between the break and AL , ft X - Separation distance of the break, ft Sonic Speed in Water versus Water Pressure Moody Equilibrium Critical Flow with Slip Extended into Subcooled Region Short Term Release Rate Calculations Short Term Release Rate Calculations Btu h := 542.6 From ASME Steam Tables f lbm ho := hf FI := 0.50 for liquid from NEDO-24548 pg.11 D := 2.5 ft Inside diameter of pipe at break down location (Assumed) DL := 0.5 ft Diameter of restriction (Assumed) LI := 26 ft The distance between break and nearest restriction Po := 1000 psi Initial pressure Short Term Release Rate Calculations (cont) lbm G := 7500 Maximum mass flux from Moody Plots c 2 ft G1 := Gc mass flux from Moody Plots 2 ft c := 1.6⋅10 sonic speed in the fluid (from Sonic Speed in Water vs. Water Pressure Figure 1 s 3. ft v:= 0.02159 specific volume of fluid initially in the pipe from ASME Steam Tables lbm 1 2 ABR := π⋅D 2 4 ABR = 4.909 ft Break Area 1 2 2 A := π⋅D A = 0.196 ft Mimimum cross sectional area between vessel and break L 4 L L 3 VI := ABR⋅LI VI = 127.627 ft Volume of the pipe between the break and AL Short Term Release Rate Calculations (cont) AL = 0.04 FI = 0.5 ABR AL If > FI ABR (2⋅LI) tI := tI = 0.325 sec c1 AL If < FI ABR VI t := I. t = 0.321 sec ABR⋅G1⋅FI⋅v I. Short Term Release Rate Calculations (cont) lb 4 MI := G1⋅ABR⋅FI MI = 1.841 × 10 sec Flow during tI 3 lb M := A ⋅G M = 1.473 × 10 Steady state flow through ss L 1 ss sec restriction after tI 4 2 .10 4 1.5 .10 4 M 1 .10 5000 Flow (lb/sec) Discharge Pipe In 0 0 0.2 0.4 0.6 0.8 tI Time after Break (sec) 31 5. Describe Origins and Use of Critical Flow Correlations 32 5. Describe Origins and Use of Critical Flow Correlations (cont.) 33 5. Describe Origins and Use of Critical Flow Correlations (cont.) 5. Describe Origins and Use of Critical Flow Correlations (cont.) 35 5. Describe Origins and Use of Critical Flow Correlations (cont.) Use of Critical Flow Correlations in Nuclear Applications • Most common use of HEM, Moody, and Henry Fauske • Used in LOCA break flow calculations • Main Steam Line Breaks • Maximum flow in a orifice • Safety Valve Opening Use of Critical Flow Correlations in Nuclear Applications (cont.) 10CFR50 Appendix K--ECCS Evaluation Models I.
Load more

Recommended publications
  • Che 253M Experiment No. 2 COMPRESSIBLE GAS FLOW
    Rev. 8/15 AD/GW ChE 253M Experiment No. 2 COMPRESSIBLE GAS FLOW The objective of this experiment is to familiarize the student with methods for measurement of compressible gas flow and to study gas flow under subsonic and supersonic flow conditions. The experiment is divided into three distinct parts: (1) Calibration and determination of the critical pressure ratio for a critical flow nozzle under supersonic flow conditions (2) Calculation of the discharge coefficient and Reynolds number for an orifice under subsonic (non- choked) flow conditions and (3) Determination of the orifice constants and mass discharge from a pressurized tank in a dynamic bleed down experiment under (choked) flow conditions. The experimental set up consists of a 100 psig air source branched into two manifolds: the first used for parts (1) and (2) and the second for part (3). The first manifold contains a critical flow nozzle, a NIST-calibrated in-line digital mass flow meter, and an orifice meter, all connected in series with copper piping. The second manifold contains a strain-gauge pressure transducer and a stainless steel tank, which can be pressurized and subsequently bled via a number of attached orifices. A number of NIST-calibrated digital hand held manometers are also used for measuring pressure in all 3 parts of this experiment. Assorted pressure regulators, manual valves, and pressure gauges are present on both manifolds and you are expected to familiarize yourself with the process flow, and know how to operate them to carry out the experiment. A process flow diagram plus handouts outlining the theory of operation of these devices are attached.
    [Show full text]
  • Aspects of Flow for Current, Flow Rate Is Directly Proportional to Potential
    Vacuum technology Aspects of flow For current, flow rate is directly proportional to potential difference and inversely proportional to resistance. I = V/R or I = V/R For a fluid flow, Q = (P1-P2)/R or P/R Using reciprocal of resistance, called conductance, we have, Q = C (P1-P2) There are two kinds of flow, volumetric flow and mass flow Volume flow rate, S = vA v – the average bulk velocity, A the cross sectional area S = V/t, V is the volume and t is the time. Mass flow rate is S x density. G = vA or V/t Mass flow rate is measured in units of throughput, such as torr.L/s Throughput = volume flow rate x pressure Throughput is equivalent to power. Torr.L/s (g/cm2)cm3/s g.cm/s J/s W It works out that, 1W = 7.5 torr.L/s Types of low 1. Laminar: Occurs when the ratio of mass flow to viscosity (Reynolds number) is low for a given diameter. This happens when Reynolds number is approximately below 2000. Q ~ P12-P22 2. Above 3000, flow becomes turbulent Q ~ (P12-P22)0.5 3. Choked flow occurs when there is a flow restriction between two pressure regions. Assume an orifice and the pressure difference between the two sections, such as 2:1. Assume that the pressure in the inlet chamber is constant. The flow relation is, Q ~ P1 4. Molecular flow: When pressure reduces, MFP becomes larger than the dimensions of the duct, collisions occur between the walls of the vessel.
    [Show full text]
  • Mass Flow Rate and Isolation Characteristics of Injectors for Use with Self-Pressurizing Oxidizers in Hybrid Rockets
    49th AIAA/ASME/SAE/ASEE Joint PropulsionConference AIAA 2013-3636 July 14 - 17, 2013, San Jose, CA Mass Flow Rate and Isolation Characteristics of Injectors for Use with Self-Pressurizing Oxidizers in Hybrid Rockets Benjamin S. Waxman*, Jonah E. Zimmerman†, Brian J. Cantwell‡ Stanford University, Stanford, CA 94305 and Gregory G. Zilliac§ NASA Ames Research Center, Moffet Field, CA 94035 Self-pressurizing rocket propellants are currently gaining popularity in the propulsion community, partic- ularly in hybrid rocket applications. Due to their high vapor pressure, these propellants can be driven out of a storage tank without the need for complicated pressurization systems or turbopumps, greatly minimizing the overall system complexity and mass. Nitrous oxide (N2O) is the most commonly used self pressurizing oxidizer in hybrid rockets because it has a vapor pressure of approximately 730 psi (5.03 MPa) at room temperature and is highly storable. However, it can be difficult to model the feed system with these propellants due to the presence of two-phase flow, especially in the injector. An experimental test apparatus was developed in order to study the performance of nitrous oxide injectors over a wide range of operating conditions. Mass flow rate characterization has been performed to determine the effects of injector geometry and propellant sub-cooling (pressurization). It has been shown that rounded and chamfered inlets provide nearly identical mass flow rate improvement in comparison to square edged orifices. A particular emphasis has been placed on identifying the critical flow regime, where the flow rate is independent of backpressure (similar to choking). For a simple orifice style injector, it has been demonstrated that critical flow occurs when the downstream pressure falls sufficiently below the vapor pressure, ensuring bulk vapor formation within the injector element.
    [Show full text]
  • Nozzle Aerodynamics Baseline Design
    Preliminary Design Review Supersonic Air-Breathing Redesigned Engine Nozzle Customer: Air Force Research Lab Advisor: Brian Argrow Team Members: Corrina Briggs, Jared Cuteri, Tucker Emmett, Alexander Muller, Jack Oblack, Andrew Quinn, Andrew Sanchez, Grant Vincent, Nathaniel Voth Project Description Model, manufacture, and verify an integrated nozzle capable of accelerating subsonic exhaust to supersonic exhaust produced from a P90-RXi JetCat engine for increased thrust and efficiency from its stock configuration. Stock Nozzle Vs. Supersonic Nozzle Inlet Compressor Combustor Turbine Project Baseline Nozzle Nozzle Test Nozzle Project Description Design Aerodynamics Bed Integration Summary Objectives/Requirements •FR 1: The Nozzle Shall accelerate the flow from subsonic to supersonic conditions. •FR 2: The Nozzle shall not decrease the Thrust-to-Weight Ratio. •FR 3: The Nozzle shall be designed and manufactured such that it will integrate with the JetCat Engine. •DR 3.1: The Nozzle shall be manufactured using additive manufacturing. •DR 3.4: Successful integration of the nozzle shall be reversible such that the engine is operable in its stock configuration after the new nozzle has been attached, tested, and detached. •FR4: The Nozzle shall be able to withstand engine operation for at least 30 seconds. Project Baseline Nozzle Nozzle Test Nozzle Project Description Design Aerodynamics Bed Integration Summary Concept of Operations JetCat P90-SE Subsonic Supersonic Engine Flow Flow 1. Remove Stock Nozzle 2. Additive Manufactured 3-D Nozzle
    [Show full text]
  • Physics 101: Lecture 18 Fluids II
    PhysicsPhysics 101:101: LectureLecture 1818 FluidsFluids IIII Today’s lecture will cover Textbook Chapter 9 Physics 101: Lecture 18, Pg 1 ReviewReview StaticStatic FluidsFluids Pressure is force exerted by molecules “bouncing” off container P = F/A Gravity affects pressure P = P 0 + ρgd Archimedes’ principle: Buoyant force is “weight” of displaced fluid. F = ρ g V Today include moving fluids! A1v1 = A 2 v2 – continuity equation 2 2 P1+ρgy 1 + ½ ρv1 = P 2+ρgy 2 + ½ρv2 – Bernoulli’s equation Physics 101: Lecture 18, Pg 2 08 ArchimedesArchimedes ’’ PrinciplePrinciple Buoyant Force (F B) weight of fluid displaced FB = ρfluid Vdisplaced g Fg = mg = ρobject Vobject g object sinks if ρobject > ρfluid object floats if ρobject < ρfluid If object floats… FB = F g Therefore: ρfluid g Vdispl. = ρobject g Vobject Therefore: Vdispl./ Vobject = ρobject / ρfluid Physics 101: Lecture 18, Pg 3 10 PreflightPreflight 11 Suppose you float a large ice-cube in a glass of water, and that after you place the ice in the glass the level of the water is at the very brim. When the ice melts, the level of the water in the glass will: 1. Go up, causing the water to spill out of the glass. 2. Go down. 3. Stay the same. Physics 101: Lecture 18, Pg 4 12 PreflightPreflight 22 Which weighs more: 1. A large bathtub filled to the brim with water. 2. A large bathtub filled to the brim with water with a battle-ship floating in it. 3. They will weigh the same. Tub of water + ship Tub of water Overflowed water Physics 101: Lecture 18, Pg 5 15 ContinuityContinuity A four-lane highway merges down to a two-lane highway.
    [Show full text]
  • THERMODYNAMICS, HEAT TRANSFER, and FLUID FLOW, Module 3 Fluid Flow Blank Fluid Flow TABLE of CONTENTS
    Department of Energy Fundamentals Handbook THERMODYNAMICS, HEAT TRANSFER, AND FLUID FLOW, Module 3 Fluid Flow blank Fluid Flow TABLE OF CONTENTS TABLE OF CONTENTS LIST OF FIGURES .................................................. iv LIST OF TABLES ................................................... v REFERENCES ..................................................... vi OBJECTIVES ..................................................... vii CONTINUITY EQUATION ............................................ 1 Introduction .................................................. 1 Properties of Fluids ............................................. 2 Buoyancy .................................................... 2 Compressibility ................................................ 3 Relationship Between Depth and Pressure ............................. 3 Pascal’s Law .................................................. 7 Control Volume ............................................... 8 Volumetric Flow Rate ........................................... 9 Mass Flow Rate ............................................... 9 Conservation of Mass ........................................... 10 Steady-State Flow ............................................. 10 Continuity Equation ............................................ 11 Summary ................................................... 16 LAMINAR AND TURBULENT FLOW ................................... 17 Flow Regimes ................................................ 17 Laminar Flow ...............................................
    [Show full text]
  • Acoustic and Aerodynamic Characteristics Of
    Aeroacoustic Characteristics of Model Jet Test Facility Flow Conditioners Kevin W. Kinzie*, Brenda S. Henderson**, and Harry H. Haskin*** NASA Langley Research Center, Hampton , VA 23681 An experimental investigation of flow conditioning devices used to suppress internal rig noise in high speed, high temperature experimental jet facilities is discussed. The aerodynamic and acoustic characteristics of a number of devices including pressure loss and extraneous noise generation are measured. Both aerodynamic and acoustic characteristics are strongly dependent on the porosity of the flow conditioner and the closure ratio of the duct system. For unchoked flow conditioners, the pressure loss follows conventional incompressible flow models. However, for choked flow conditioners, a compressible flow model where the duct and flow conditioner system is modeled as a convergent-divergent nozzle can be used to estimate pressure loss. Choked flow conditioners generate significantly more noise than unchoked conditioners. In addition, flow conditioners with small hole diameters or sintered metal felt material generate less “self-noise” noise compared to flow conditioners with larger holes. Nomenclature AR = duct closure ratio CB = counterbored flow conditioner d1 = flow conditioner minimum hole diameter d2 = flow conditioner counterbore hole diameter FCPR = flow conditioner pressure ratio OPR = operating pressure ratio POA = percent open area; porosity l1 = flow conditioner counterbore depth L = flow conditioner thickness mic = flow conditioner with microholes K = pressure loss coefficient st = flow conditioner with straight through holes; no counterbore StD = Strouhal number based on exit orifice diameter and velocity Stfc = Strouhal number based on flow condition hole diameter and velocity U = flow velocity θ = directivity angle ρ = density I.
    [Show full text]
  • Introduction to Chemical Engineering Processes/Print Version
    Introduction to Chemical Engineering Processes/Print Version From Wikibooks, the open-content textbooks collection Contents [hide ] • 1 Chapter 1: Prerequisites o 1.1 Consistency of units 1.1.1 Units of Common Physical Properties 1.1.2 SI (kg-m-s) System 1.1.2.1 Derived units from the SI system 1.1.3 CGS (cm-g-s) system 1.1.4 English system o 1.2 How to convert between units 1.2.1 Finding equivalences 1.2.2 Using the equivalences o 1.3 Dimensional analysis as a check on equations o 1.4 Chapter 1 Practice Problems • 2 Chapter 2: Elementary mass balances o 2.1 The "Black Box" approach to problem-solving 2.1.1 Conservation equations 2.1.2 Common assumptions on the conservation equation o 2.2 Conservation of mass o 2.3 Converting Information into Mass Flows - Introduction o 2.4 Volumetric Flow rates 2.4.1 Why they're useful 2.4.2 Limitations 2.4.3 How to convert volumetric flow rates to mass flow rates o 2.5 Velocities 2.5.1 Why they're useful 2.5.2 Limitations 2.5.3 How to convert velocity into mass flow rate o 2.6 Molar Flow Rates 2.6.1 Why they're useful 2.6.2 Limitations 2.6.3 How to Change from Molar Flow Rate to Mass Flow Rate o 2.7 A Typical Type of Problem o 2.8 Single Component in Multiple Processes: a Steam Process 2.8.1 Step 1: Draw a Flowchart 2.8.2 Step 2: Make sure your units are consistent 2.8.3 Step 3: Relate your variables 2.8.4 So you want to check your guess? Alright then read on.
    [Show full text]
  • Dimensional Analysis and Modeling
    cen72367_ch07.qxd 10/29/04 2:27 PM Page 269 CHAPTER DIMENSIONAL ANALYSIS 7 AND MODELING n this chapter, we first review the concepts of dimensions and units. We then review the fundamental principle of dimensional homogeneity, and OBJECTIVES Ishow how it is applied to equations in order to nondimensionalize them When you finish reading this chapter, you and to identify dimensionless groups. We discuss the concept of similarity should be able to between a model and a prototype. We also describe a powerful tool for engi- I Develop a better understanding neers and scientists called dimensional analysis, in which the combination of dimensions, units, and of dimensional variables, nondimensional variables, and dimensional con- dimensional homogeneity of equations stants into nondimensional parameters reduces the number of necessary I Understand the numerous independent parameters in a problem. We present a step-by-step method for benefits of dimensional analysis obtaining these nondimensional parameters, called the method of repeating I Know how to use the method of variables, which is based solely on the dimensions of the variables and con- repeating variables to identify stants. Finally, we apply this technique to several practical problems to illus- nondimensional parameters trate both its utility and its limitations. I Understand the concept of dynamic similarity and how to apply it to experimental modeling 269 cen72367_ch07.qxd 10/29/04 2:27 PM Page 270 270 FLUID MECHANICS Length 7–1 I DIMENSIONS AND UNITS 3.2 cm A dimension is a measure of a physical quantity (without numerical val- ues), while a unit is a way to assign a number to that dimension.
    [Show full text]
  • Flow Measurement Using Hot-Film Anemometer
    Flow basics Basics of Flow measurement using Hot-film anemometer Version 1.0 1/9 Flow basics Inhaltsverzeichnis: 1. Definitions 1.1. Air Velocity 1.2. Amount (of Gas) 1.3. Flow 1.3.1. Mass flow rate 1.3.2. Volumetric flow rate 1.3.3. Standard volumetric flow rate 2. Flow formulas 3. Flow measurements using E+E Hot-film anemometer Version 1.0 2/9 Flow basics 1. Definitions: 1.1. Air Velocity: Definition: „Air Velocity describes the distance an air molecule is moving during a certain time period “ Units: Name of unit shift Converted to SI - Unit m/s Meter per second m/s 1 m/s Kilometer per hour km/h 0,277778 m/s Centimeter per minute cm/min 1,666667 · 10-4m/s Centimeter per second cm/s 1 · 10-2 m/s Meter per minute m/min 1,66667 · 10-2 m/s Millimeter per minute mm/min 1,666667 · 10-5 m/s Millimeter per second mm/s 1 · 10-3 m/s Foot per hour ft/h, fph 8,466667 · 10-5 m/s Foot per minute ft/min, fpm 5,08 · 10-3 m/s Foot per second ft/s, fps 0,3048 m/s Furlong per fortnight furlong/fortnight 1,66309 · 10-4 m/s Inch per second in/s, ips 2,54000 · 1-2 m/s Knot kn, knot 0,514444 m/s Kyne cm/s 1 · 10-2 m/s Mile per year mpy 8,04327 · 10-13 m/s Mile (stat) per hour mph, mi/h 0,44704 m/s Mile (stat) per hour mi/min 26,8224 m/s Version 1.0 3/9 Flow basics 1.2.
    [Show full text]
  • Space Advantage Provided by De-Laval Nozzle and Bell Nozzle Over Venturi
    Proceedings of the World Congress on Engineering 2015 Vol II WCE 2015, July 1 - 3, 2015, London, U.K. Space Advantage Provided by De-Laval Nozzle and Bell Nozzle over Venturi Omkar N. Deshpande, Nitin L. Narappanawar Abstract:-The FSAE guidelines state that it is mandatory for many crucial components are to be fitted in a very little each and every car participating in the said event to have a space. Therefore there is a need to design a new kind of single circular 20mm restrictor in the intake system. All the air nozzle achieving optimality at a higher angle than that of the flowing to the engine must pass through this restrictor. Conventionally, a Venturi Nozzle is used as a restrictor. In our venturi nozzle. For this purpose De Laval Nozzle and Bell research, we have proposed two Nozzles: De-Laval Nozzle and Nozzle are analyzed as a possible alternative to the venturi. Bell Nozzle as an alternative to the Venturi Nozzle. After De- Laval Nozzle is used in certain type of steam turbines numerous CFD Simulations; we have inferred that the results and also as a Rocket Engine Nozzle [6]. Bell Nozzle is also of the De-Laval Nozzle and Bell Nozzle are similar to the widely used as a Rocket Engine Nozzle. Both of the nozzles Venturi Nozzle. Along with providing similar results, the two achieve optimality at a higher angle of convergence as nozzles provide a space saving of 6.86% over the Venturi Nozzle. The data was gathered from SolidWorks Flow demonstrated in ‘Section V parts A.); B.).’ Simulation 2014.
    [Show full text]
  • Momentum and Dimensional Analysis
    Performance 5. More Aerodynamic Considerations There is an alternative way of looking at aerodynamic flow problems that is useful for understanding certain phenomena. Rather than tracking a particle of fluid, we can isolate a region of the fluid (called a control volume) and observe the effects of forces (of all kinds) on the fluid that is in that control volume. It should be noted that the fluid in the control volume is changing with time, as some enters and some leaves. (Sometime such problems are called variable mass problems because the mass in the control volume is changing). Again, for the purposes of this course it is convenient to restrict our attention to fluid flow through a stream tube or a duct of some sort, i.e. one-dimensional flow. To start, we will consider flow in a duct and divide it into two overlapping chunks of fluid. The initial chunk of fluid is the fluid that includes regions A and B and is observed at time t1. The second chunk of fluid contains the same fluid particles that have moved to a new position indicated by regions B and C. Hence the region B is common to both. We can now apply Newton’s second law to the same group of fluid particles. At time t1 the particles occupy region AB, and at time t2 the particles occupy region BC. We can write Newton’s laws regarding the change in momentum of the particles from time 1 to time 2: (1) If we designate ( ) my , Eq. (1) becomes: (2) or (3) We now focus on the region B.
    [Show full text]